Stumbling / bucking in second gear @ 2000 - 3000 RPM

[BMillar]

I've searched hard and haven't found the answers I need. (Please no flames - if there is a relevant thread, I'd be very grateful to be pointed in the right direction ).

1991 car w 27K mile manual tranny. In second gear at 2000 - 3000 RPM the drive train is bucking and stumbling on acceleration. In neutral engine revs smooth as silk. Almost feels like the clutch is failing, but I don't seem to have any other issues throughout the gears or RPM ranges. Drive train feels fine in second gear as long as the RPMs are kept well above 2K. Ideas?

 

[Old Guy]

I've searched hard and haven't found the answers I need. (Please no flames - if there is a relevant thread, I'd be very grateful to be pointed in the right direction ).

1991 car w 27K mile manual tranny. In second gear at 2000 - 3000 RPM the drive train is bucking and stumbling on acceleration. In neutral engine revs smooth as silk. Almost feels like the clutch is failing, but I don't seem to have any other issues throughout the gears or RPM ranges. Drive train feels fine in second gear as long as the RPMs are kept well above 2K. Ideas?

The all important question - have you used the SC connector to determine if there are any stored error codes in the ECU. Not all error codes will cause the CEL to illuminate immediately. If there are error codes that may give you a clue as to what is going on.

So this problem only occurs in 2nd gear, not 1st of 3rd …..? If the problem doesn't occur in 1st then I doubt you have clutch issues. Stumbling seems more like a fuel delivery / fuel mixture issue or perhaps an ignition problem which tend to materialize when the engine is under heavy load. However, I would expect that problem to also emerge in 3rd, 4th if you press the throttle down at 2000 RPM. So many possible causes for fuel and ignition problems.
- fuel pressure problems
- dirty fuel injectors
- O2 sensor problems
- failing ignition coils
- probably a bunch of other stuff

Is your traction control becoming active when the problem occurs? A weird TCS problem can result in the engine output being restricted by the TCS.

You need to do a little more diagnosis to narrow down the source of your problem.

 

[BAVARIA]

Bucking 2-3000 rpm

OldGuy much more experienced and knowledgeable than I but I'll just throw this out there since it was my experience. /94 MT with approx 35K miles at the time -- subtle miss from 2000-2500 rpm when in 2nd gear. It turned out to be one bad spark plug. Hope OP gets this sorted out.

Best,
Jeff

 

[Bram]

Yup, I had the similar issue and it turned out to be a bad plug too, water got into the IG/coil and caused the plug to Mal function. I would check the rear bank set of IG Coil and plugs.
Also, my car had about 25K miles

Bram

 

[BMillar]

Gents, thank you for the tips. I wasn't able to work on the car this weekend due to family commitments. I've not checked for stored codes, so will do that. Interesting that two of you guys found similar issues were caused by bad plugs. I'll probably put in a new set of plugs just for good measure. I'll report back on my findings/fix. Thanks

 

[Old Guy]

If you are going to replace the plugs, check the nose of the coils for evidence of tracking / flashover. Moisture that makes its way down into the sparkplug well can cause tracking problems on the spark plug porcelain. If you see tracking on the porcelain you will almost assuredly have problems with the coil nose. Depending on severity this may require replacement of the coils. Also, check the exposed laminations on the bottom of the coil body. Surface rust that can be easily removed with a 3M scuff pad is not an issue. Severe rust that results in spreading of the laminations usually means a trip to the garbage can.

If your current plugs are Denso or NGK iridium, be aware that they can be counterfeit - especially if you got them for a really good price. Counterfeit platinum doe not seem to such an issue. The counterfeits wear out quickly. They definitely won't make it to the 60,000 mi mark.

 

[hondasash]

Had an comparable issue Last year... only in low rpm... Bad spark plug as well.
One of these 6 tends to get worse due to Rain/water eg after washing the car for instance